In a normal elevator system, speed, acceleration, and jerk rate of each elevator are set in advance and not changed.
In contrast, in a conventional elevator apparatus disclosed in, for example, Japanese Patent No. 3029883, either means for speeding up a floor-to-floor moving time of each elevator or means for slowing down the floor-to-floor moving time of each elevator is selected depending on a traffic condition. Means for increasing the speed or acceleration of the car is used as the means for speeding up the floor-to-floor moving time of each elevator.
In this elevator apparatus, however, the in-cage load is not considered as a condition for changing the speed, the acceleration, and the jerk rate. This means that a hoisting machine (motor) capable of enduring high speed and high acceleration even in a fully occupied condition is required. This incurs a substantial increase in the cost of the whole elevator system.
Further, in many recent elevator systems, as soon as a passenger presses a call button in an elevator hall, a hall lantern is lit to inform the passenger of a responding unit. The estimated clock time at which a car of each elevator arrives at each floor constitutes a basis for such preannouncement of the responding unit. However, in the case where a plurality of elevator cars exist, when they are caused to travel at different speeds, accelerations, and jerk rates from each elevator, the process of estimation produces an error leading to a wrong preannouncement.
In addition, for example, JP 2001-278553 A discloses a method for increasing acceleration or jerk rate to its upper limit when the in-cage load is within a predetermined range.
In this elevator apparatus, however, since the maximum speed of the car is not changed while acceleration and jerk rate are changed, the traveling time of the car is not drastically reduced. In particular, when the car travels a long distance, the traveling time can be substantially reduced by increasing the speed. Still, a mere increase in acceleration and jerk rate does not lead to a significant reduction in traveling time.